Moderately reduced ATP levels promote oxidative stress and debilitate autophagic and phagocytic capacities in human RPE cells.

Purpose: Aging of the RPE is associated with a decrease of intracellular ATP levels and increased oxidative stress. We investigated the effects of moderate energy deficit on intracellular glutathione levels, oxidative damage of cellular proteins and DNA, and autophagy rates using an RPE cell culture model. Additionally, phagocytosis of photoreceptor outer segments was assayed as an example of an ATP-dependent normal function of the RPE.

Effects of lipid peroxidation-related protein modifications on RPE lysosomal functions and POS phagocytosis.

Purpose: Lipofuscin accumulation in the RPE is a common downstream pathogenic pathway in various monogenic and complex retinal diseases including age-related macular degeneration (AMD). Lipid peroxidation-induced modification of proteins is thought to play a role in lipofuscinogenesis and may contribute to RPE dysfunction. A prior study demonstrated that a variety of lipofuscin-associated proteins are damaged by aberrant covalent modifications of malondialdehyde (MDA) and 4-hydroxynonenal (HNE).

Accumulation of A2-E in mitochondrial membranes of cultured RPE cells.

Background: Lipofuscin occurs in association with various blinding diseases, including ARMD. Formation of lipofuscin is considered to be initiated by the inability of the RPE lysosome to degrade constituents of phagocytosed material resulting in its intralysosomal accumulation. Thus, the deposition of abnormal retinoid adducts causing the autofluorescent properties of RPE lipofuscin originates from abnormal products of the retinoid cycle contained in phagocytosed photoreceptor outer segments.

Temperature dependent fluorescence of A2-E, the main fluorescent lipofuscin component in the RPE.

Purpose: A2-E is the dominant fluorophore of lipofuscin in the retinal pigment epithelium. In an in-vitro setup, we determined the temperature-dependent changes of the A2-E fluorescence with the aim of also assessing the potential value of such measurements for determining retinal temperature by autofluorescence measurements during laser treatment.

Methods: A2-E was biosynthesized and diluted in Dimethyl Sulfoxide (DMSO) to 1 microM.

Visualization of retinal pigment epithelial cells in vivo using digital high-resolution confocal scanning laser ophthalmoscopy.

Purpose: To visualize retinal pigment epithelial cells in vivo by fundus autofluorescence imaging using a confocal scanning laser ophthalmoscope.

Design: Experimental study and observational case report.

Methods: Digital in vivo autofluorescence images were recorded with a confocal scanning laser ophthalmoscope (excitation, 488 nm; emission, >500 nm) and compared with confocal scanning laser ophthalmoscope and fluorescence microscopic recordings from human donor eyes.

Proteins modified by malondialdehyde, 4-hydroxynonenal, or advanced glycation end products in lipofuscin of human retinal pigment epithelium.

Purpose: Lipofuscin (LF) accumulation in the retinal pigment epithelium (RPE) is associated with age and various retinal diseases. Toxic LF compounds may interfere with normal RPE function. Oxidative modification of proteins was determined in LF granules from human eyes.

Agreement among ophthalmologists in evaluating fluorescein angiograms in patients with neovascular age-related macular degeneration for photodynamic therapy eligibility (FLAP-study).

Objective: To determine intraobserver and interobserver variation for classifying types of choroidal neovascularizations (CNV) in exudative age-related macular degeneration (ARMD).

Design: Intraexaminer and interexaminer reliability study.

Participants: Digital high-quality fluorescein angiograms of 40 patients with neovascular ARMD were evaluated independently by 16 retinal specialists.

Isolation of intact lysosomes from human RPE cells and effects of A2-E on the integrity of the lysosomal and other cellular membranes.

Background: Accumulation of lipofuscin in RPE cells occurs with age and in association with various retinal diseases. Lipofuscin and its major retinoid compound and fluorophore A2-E interfere with the cellular metabolism of RPE cells in various ways. One of these mechanisms is thought to be related to detergent properties of A2-E.

Indocyanine green angiography in the presence of subretinal or intraretinal haemorrhages: clinical and experimental investigations.

Purpose: The absorption and emission characteristics of indocyanine green are associated with better penetration through ocular pigments, including melanin and blood, in comparison with fluorescein. Therefore, it has been assumed that indocyanine green angiography (ICG-A) allows better delineation of fluorescent structures including choroidal neovascularization in the presence of haemorrhages. The degree and frequency of blockage by haemorrhages during ICG-A and fluorescein angiography (Fl-A) were compared and absorption characteristics by blood were experimentally determined.